This invention relates to a closure for a container, and particularly to, a container used in the water bottling industry for water dispensers and water coolers, such as a five-gallon container.
Drinking water has been supplied to consumers for many years in large containers, which typically have volumes ranging from 2.5 to 6 gallons. These large containers are often mounted upside down on a dispensing device which may also cool or heat the water as desired. The dispensing devices also permit facile dispensing of the water. A typical large container has an upstanding neck, defining an opening for the container, and has an external snap formation for engagement with a closure. Closures for the large containers are also known and typically include a roof portion, a shoulder portion depending downwardly from the roof portion, and a skirt portion depending downwardly from the shoulder portion. Internally, the closure has a snap bead, located generally at the intersection between the skirt portion and the shoulder portion, for complementary engagement with the snap formation on the container neck.
The closure may either be a “flat-roof” or a “non-spill” closure, both of which are known in the industry. A flat-roof closure has a generally flat, closed-off roof portion, which is in the form of a disc. The flat-roof closure therefore needs to be removed from the neck of the container in order to discharge the fluid or contents of the container.
There is a relatively high degree of standardization in the water bottling industry, such that most closures for large containers have many corresponding, or similar features. In addition, many of the dimensions for closures are required to lie within relatively tight tolerances, in order for the closures to provide an effective liquid-tight seal on a range of conventional container neck finishes. Accordingly, design freedom for such closures is limited.
Because closures of this type need to fit over a relatively large neck and provide a reliable seal to a high-volume container, the closures tend to be relatively bulky and heavy. It would nevertheless be desirable to be able to reduce the weight of a closure. One approach would be to reduce the overall wall thickness of the closure. While it is possible to mold a closure having an overall thinner wall thickness, this has resulted in a number of problems. First, by providing thinner walls, the closures are weaker and more prone to cracking under stress. Second, the wall of the closure is more susceptible to being deformed when the thinned-walled closure is urged onto a container neck, because the force applied can be sufficient to deform the shoulder portion, which also causes a corresponding deformation of the internal snap bead. These deformations may prevent correct application of the closure onto the container neck and lead to an inadequate seal being formed.
In order to counter this problem, such a closure is generally formed with an internal snap bead diameter that is greater than would otherwise be required for the snap bead to engage a conventional container neck snap formation. Therefore, even when the closure is applied to a container neck correctly (i.e. without being deformed in the above manner) the quality of the seal provided may be limited by the difference between the diameters of the closure's snap bead and the external snap formation on the container neck.
A further concern regarding closures for large containers is the relatively large amount of material mass incorporated into the closure, especially in light of their single use. As explained more fully below, certain portions of the closure incorporate relatively thick cross sections for historical functional reasons. This is wasteful and uneconomical because as technology evolved, some of the reasons for these thick sections no longer apply. Therefore, it is desired to have closures aimed at savings in weight, processing time, and even improved appearance, but which is still capable of providing an effective seal and capable of maintaining its integrity.